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A244986 a(n) = Position of 2^n among the numbers which are divisible by the square of their highest noncomposite factor (i.e., the union of {1} and A070003), 0 if not there. 3
1, 0, 2, 3, 5, 9, 14, 23, 37, 58, 90, 143, 225, 355, 563, 894, 1426, 2277, 3643, 5839, 9398, 15155, 24518, 39758, 64607, 105250, 171874, 281237, 461255, 758040, 1248270 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..30.

FORMULA

For all n >= 1, a(n+1) = A244984(A006254(n)).

EXAMPLE

2 is not divisible by 2^2, thus a(2) = 0, the only zero in the sequence.

2^4 = 16 is the fifth term in [1, 4, 8, 9, 16, 18, 25, 27, 32, 36, ...] (the union of {1} and A070003), thus a(4) = 5.

2^5 = 32 is the ninth term in the same list, thus a(5) = 9.

CROSSREFS

From a(2) onward one more than A244985.

Cf. A000079, A070003, A006254, A244984.

Sequence in context: A056686 A326332 A079962 * A293547 A124502 A251572

Adjacent sequences:  A244983 A244984 A244985 * A244987 A244988 A244989

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jul 21 2014

STATUS

approved

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Last modified December 1 14:10 EST 2021. Contains 349430 sequences. (Running on oeis4.)